Metagenome-assembled-genomes recovered from the Arctic drift expedition MOSAiC

Abstract

The Multidisciplinary Observatory for Study of the Arctic Climate (MOSAiC) expedition consisted of a year-long drifting survey of the Central Arctic Ocean. The ecosystems component of MOSAiC included the sampling of molecular data, with metagenomes collected from a diverse range of environments. The generation of metagenome-assembled-genomes (MAGs) from metagenomes are a starting point for genome-resolved analyses. This dataset presents a catalogue of MAGs recovered from a set of 73 samples from MOSAiC, including 2407 prokaryotic and 56 eukaryotic MAGs, as well as annotations of a near complete eukaryotic MAG using the Joint Genome Institute (JGI) annotation pipeline. The metagenomic samples are from the surface ocean, chlorophyll maximum, mesopelagic and bathypelagic, within leads and under-ice ocean, as well as melt ponds, ice ridges, and first- and second-year sea ice. This set of MAGs can be used to benchmark microbial biodiversity in the Central Arctic Ocean, compare individual strains across space and time, and to study changes in Arctic microbial communities from the winter to summer, at a genomic level.

Fig. 1

Map showing the locations of the samples. Panel A shows the overall course of the drift, and locations of the samples. Panel B shows more detailed locations, zoomed within the boxes marked in panel A. Samples are from leg 2 (15^th Dec. 2019–3^rd March 2020), leg 3 (3^rd March–6^th June 2020), and leg 4 (6^th June–12^th August 2020), with the drift route generally moving southward from the Central Arctic Ocean. Often, multiple (replicate) samples are co-located, either from the same CTD cast, or as different layers within a single ice core. In panel B the number of co-located samples is represented by the size of the marker.

Fig. 2

A summary of the IMG metagenome annotation pipeline, and the coassembly pipeline used for the two sample sets; either the pilot samples or the HAVOC samples. Coloured boxes indicate intermediate folders or files, either one per sample in the case of the stacked boxes, or one for each sample set, in the case of the coassemblies. Arrows indicate which files are inputs and outputs for other processes.

Fig. 3

Completeness and contamination of the 2463 MAGs recovered across the 73 samples; 2407 prokaryotic and 56 eukaryotic MAGs. In each panel, a vertical line separates the eukaryotic and prokaryotic MAGs. The number of MAGs per taxon is shown between the two boxplots.

Fig. 4

Phylogenetic trees showing MAGs from singly assembled samples (left) and MAGs from coassemblies (right). Reference genomes, common to both trees, have their leaves aligned and are labelled at the centre of the tree, with collapsed clades represented in the tree by a wedge. Some leaves of reference genomes are unlabelled for legibility, where they share their genus with their closest relative in the tree. MAGs labelled are shown on the tips of each tree. For each MAG, the colour of the background indicates the type of the sample (or indeterminate type, in the case of the coassemblies). The coassembled MAG havoc.90, marked with an asterisk *, had good completeness and contamination scores and was subsequently renamed Bacilliariophyceae sp. MOSAICH1_1.